Vacuum Sewage Systems

In 1865 it seems that some people in Amsterdam noticed they were polluting the river Elz with human waste. Hauling odiferous material out of the castle on wagons was unpopular also.

In 1985, I was working on a commercial office building project at Grissom Air Force Base, Indiana. The mechanical contractor on the project was based in the little town of Rochester, Indiana.

One day I had the privilege of being invited to tour Burton Mechanical Contractor’s facility, and I was pleased to meet Mr. Burton himself. One achievement he took great pride in was their patented vacuum sewage system called AirVac.

You can find their website at www.airvac.com. Recently I noticed on Air Vac's Web site that a system had been installed at Ocean Shores in Washington State. Ocean Shores is a large real estate development on a flat sandy peninsula that separates Grays Harbor from the Pacific Ocean. The AirVac system had been installed using 96 miles of vacuum sewer lines serving over 10,000 lots.

Vacuum sewage systems are commonplace on aircraft, trains, and ships. The installation of a vacuum system in place of a gravity sewer system in real estate development is coming of age. The benefits are obvious.
• The hazards and cost of digging deep trenches for a gravity sewer main can be avoided.
• Forced (pressure pumped) sewer lines and gravity lines always have the potential for leaks. Gravity line water infiltration is a big problem too.
• In locations where ground water is a problem, a vacuum system can be installed at shallow depths.
• Vacuum systems use a lot less water. Not only is water saved but the concentration of organic matter in the black water is higher allowing fermentation and bio-gas production.
• Less water means smaller pipes are used, which equates to lower installation and maintenance costs.
• Grease buildup is a major maintenance cost in gravity systems. The fast moving waste in a vacuum system does not allow grease to build up.
• Sewer odors and sewer gas have little or no outlet. A gravity system has numerous manholes with lids that allow rainwater in and foul smells out.

The flat terrain, high water table, and environmental sensitivity of coastal areas like Ocean Shores are ideally suited for a vacuum sewage system.

In 1865, T. Charles Lienur was asked to design a sewer system for the Castle Luxembourg in Amsterdam. It seems that some people noticed they were polluting the river Elz. Hauling odiferous material out of the castle on wagons was unpopular also.

Lienur developed a system using two pipes: one provided water and the other was used to transport waste water. Few other details are known about the Lienur system, but it was certainly a vacuum system. Vacuum toilets were also developed, and by 1906 over 4,500 of them were in use in Amsterdam and connected to the Lienur vacuum sewer system.

Modern vacuum sewer systems, like the AirVac, work by creating a vacuum in the sewer main (16-20 Hg). A vacuum pump at a pump station keeps the system under a constant vacuum. A valve is installed at each entry point to the system inside a valve pit. Sewage enters the pit by gravity from the building sewer pipe. The pit is typically located near the building or in a location where multiple buildings can utilize it.

The pit valve opens automatically when a given amount of sewage accumulates in the sump. The difference between the atmospheric pressure and the vacuum pressure in the main causes the valve to open, and the sewage is forced into the main, emptying the contents of the sump and sending the sewage along its way to the pump station with a volume of atmospheric air behind it.

Vacuum sewer systems are ideally suited for development sites with ground water problems, hard rock excavations, deep trenches, flat topography and environmentally sensitive sites.

After over 140 years, vacuum sewage systems should be more widely used.